Securing valuables by lock is a part of people's daily life. Since locking the apartment door is a routine task, this fact may be easily forgotten. This invention brings peace of mind to all those, who have at least once asked themselves: “Did I lock the door?” The present invention provides design embodiments for a device that can be attached to common keys and methods for use thereof, as well as user information, such as time and/or the action performed (locking or unlocking).
U.S. Pat. No. 2,198,484 to Merkl particularly claims ‘Indicator Key’ as follows: “In a key, the combination of a bit provided with an indicator end, said end being provided with a slot, an operating handle movably mounted on said bit end, said handle being provide with a stop pin projecting in said slot to limit the motion of the handle over a predetermined arc, and means, operatively associated with said indicator end and said handle and independent of said pin and slot, for positioning said handle on said end at the limits of said arc.”
There is known a ‘lock position indicator’ according to U.S. Pat. No. 4,440,011 to Klein, teaching “A casing for holding a key in one of two pivoted positions. The key pivots about an axis extending along one edge thereof when a lock is turned by the user of the key. An indicator may be attached to the key for extension through a small opening in the casing or housing when the key is in one position and for retraction below the level of the casing periphery when the key is in the opposite position. In a second embodiment, a portion of the casing may be pierced along three edges and arranged so that, when the key is in one position, the pierced portion is pushed above the casing periphery and, when the key is pivoted to the second position, the pierced portion is coextensive with or below the casing periphery. In a third embodiment, an indicator may be pivotally fastened in position between halves of the casing for movement (a) above and (b) even with or below the periphery of the casing when the key is pivoted.”
A ‘locking key’ is shown in U.S. Pat. No. 4,631,943 to Hoener, describing “A locking key, designed to preserve an indication of the lock-shifting (opening or closing) operation last performed, has a shank with an extension shaft rotatably received in an adjoining head, the relative rotation of the shank and the head being limited to 90.degree. or 180.degree. by a retaining pin in the head coacting with a part-circular recess on the shaft. The pin and the recess also serve to hold the head in a fixed axial position with reference to the shank. A spring-loaded detent in the shaft or elsewhere inside the head serves to index the two key portions in either of their limiting relative positions.”
According to U.S. Pat. No. 5,595,080 to Hoener, “A lock condition indicator device which is adapted for affixation to a key for a cylinder lock has a substantially circular movable means adapted to be retained in juxtaposition to a head portion of the key, but rotatable about a longitudinal axis of the key when an engaging means on the circumference of the movable means encounters an obstructing means on an outer surface of the lock, resulting in the movable means being rotated into one of a plurality of indicator positions.”
Another prior art example is U.S. Pat. No. 6,575,005 to Hunter describes “A locked/unlocked indicator for a key that shows whether a person has locked a door lock or any type of lock. The indicator has a base member having a window formed in the top surface that communicates with a channel formed in the bottom surface. A slide member has a thumb tab that extends upwardly through the aperture that allows the slide member to be slid back and forth between a position that indicates whether the door lock is locked or unlocked. The bottom of the slide member is a spring member that has curved lips on the front and rear end that make an audible sound when the slide member reaches both the locked and the unlocked position. The base member has adhesive on the bottom surface for attachment to the head member of a key.”
There is known U.S. Pat. No. 6,935,147 to St. Felix describing ‘Key with indicator and retractable shield’, wherein: “The key with a lock-unlock indicator is operable with a complementary lock set. The key has a body and an elongated key stem extending therefrom. A toggle bar is pivotally mounted or disposed on the key stem. The toggle bar operates in conjunction with a lock cam and an unlock cam mounted on the face of the complementary lock set. When the operator turns the key in one direction, the lock cam motivates the toggle bar thereby shifting its position. An indicator disposed in the key body displaying a lock condition and an unlock condition. The lock cam is shielded with a retractable shield.”
Another U.S. Pat. No. 6,886,382 to St. Felix teaches “The key with a lock-unlock indicator is operable with a complementary lock set. The key has a body and an elongated key stem extending therefrom. A toggle bar is pivotally mounted or disposed on the key stem. The toggle bar operates in conjunction with a lock cam and an unlock cam mounted on the face of the complementary lock set. When the operator turns the key in one direction, the lock cam motivates the toggle bar thereby shifting its position. An indicator disposed in the key body displaying a lock condition and an unlock condition.”
The U.S. Pat. No. 6,886,382 discloses: “FIG. 6 diagrammatically illustrates an electronic lock-unlock indicator. Toggle 16 operates electrical switch 50 when the toggle 16 passes the switch. For example, a rocker switch or a other micro switch may be utilized on key stem 14 proximate the toggle and key body 12. Disposed in key body 12 is a battery 52; a visual display unit 54, and audible announcer 56, a signal conditioning circuit 58, and a reset button 60. Switch 50 is connected to the signal conditioner 58. The signal conditioner generates appropriate electronic signals to operate display 54 and audible announcer (speaker) 56. Display 54 shows a locked or unlocked word, symbol or color. Reset switch 60 permits the operator to reset the signal conditioner if the key body 12 erroneously indicates a locked or unlocked condition. Battery 52 is replaceable. Display 54 is visible to the user. Display 54 may be on an edge of the key or may be on either side or the back end of the key body.”
Although there have been many mechanical designs for indicator devices that show the last action (lock or unlock) performed using a key, the element of time is usually neglected. None of the above examples of prior art exhibits any indication that the locking time information is available to the user in the mentioned devices.